Answer:
The value of n = 9th term
Explanation:
Given:
In an arithmetic series
a3 = 15
d = -3/2
an = 6
Find:
The value of n
Computation:
In an arithmetic series
An = a + [n - 1]d
where,
An = last term
a = first term
n = number of term
d = common difference
So,
a3 = a + 2d
15 = a + 2(-3/2)
15 = a - 3
a = 18
An = a + [n - 1]d
6 = 18 + [n - 1][-3/2]
-12 = [n-1][-3/2]
8 = n - 1
The value of n = 9th term